The image is from GSM Arena. The phone Infinix has only 45W charge capability yet it does slightly faster than two other phones with much faster charging rates(and same battery capacity).
I know some phones throttle charging speeds but that is usually post 80% threshold. Why the discrepancy then?
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I don’t understand that chart really, but charging speed is carefully controlled in the phone, based on monitoring the battery temperature among other things. They won’t charge from 0% to 80% at 100 watts even if they might hit 100W momentarily under the right conditions. Fast charging is hard on batteries anyway. Make sure you are ok with replacing the battery every so often, if you’re going to fast charge regularly.
Yep, this is it.
They are trading battery longevity for faster charging.
Personally, I generally prefer battery longevity, since that is the main factor that causes me to buy a new phone.
This is also the main reason I would like to buy a Fairphone for my next phone. I can get a new battery for $50 and replace it myself. And with 8-10 years of updates, I figure I can actually use it for 8 years with two battery replacements along the way.
It’s actually not entirely that simple, there are a bit more nuance in this. They definitely do trade a bit of battery longevity, but sacrificing longevity alone won’t give you 100W on a battery that typically can only do 45W, you will get it bursting into flame instead.
Rather, many of those Chinese phones that charge at super high power were double-cell or multi-cell designs. A multi-cell battery would allow you to reach much higher charging current under the same voltage while generating less heat due to lower resistance between terminals. But multi-cell batteries are inherently less space efficient than single cell batteries.
So they took different priorities and also traded space efficiency for charging speed, and of course this trade also means they have to trade other things to get back the space for battery, such as size of speakers (and therefore speaker audio quality) for example.
On the other hand many of those Chinese phones also don’t abide by standard protocols even way before PPS became a thing, and many of them required their own vendor’s proprietary charger to get the marketed charging speed, which have a VERY non-standard voltage, so that they can keep current low by raising voltage higher than standard USB/PD voltages, to keep the power high. This often also meant you need not only the vendor’s proprietary charger, but also their proprietary cable too because their non-standard charging voltage is also beyond the voltage that’s standard for USB cables. This principle is common now with PD chargers (like for charging a laptop for example), but they have been doing this way before PD protocol, so they have their own choices of voltage/current combos that are incompatible with PD protocol. And of course those Chinese companies like Xiaomi and Huawei would never give a flying F about complying to established industry standards and avoid vendor lock-in, customer rights be damned lol
Maybe battery cell count is a factor.
Some devices taper off their fast charging faster than others. It doesn’t have to be at 80%. Just as an example you can see the charts in the charging review for the S24 Ultra here: https://www.chargerlab.com/charging-review-of-samsung-s24-ultra/. A fun fact is that since Samsung 45W tapers off so much there isn’t much difference compared to their 25W charging. The difference is 10mins at best. Sometimes the 45W can be just a hair slower even.
As a Samsung owner, yep. I’ve done comparisons between some Samsungs and was surprised that a “slower” charge phone sometimes would charge as fast as a “faster” one, when battery size was accounted for.
I wonder how phone size, battery placement, and materials play into this.
Being able to dissipate more heat while charging will help significantly too.
I’ve had a phone with a ceramic back that would die in minutes in cold weather if I didn’t keep it in my internal coat pocket. It charged much faster than another phone that had a plastic back with a similar battery size and charging capability, even using “slow” charging (using a lower power charger). I can only assume the heat dissipation made a difference as the ceramic one never got even very warm while the plastic one did.
So maybe a combination of everything mentioned here - charge control in the phone, how the controller manages cells, location of battery in phone/heat dissipation, power optimizing while charging (do all of these phones support pass-through? That would influence charge time), etc.
Maybe it’s keeping constant 45w instead of tapering off the more charged it is
